The primary specific aims for this pilot Phase II studies are: 1. To determine complete recanalization and early clinical recovery rates in patients treated with intravenous TPA and continuously monitored with an external ultrasound compared to those treated with standard TPA dose alone. 2. To determine if continuous monitoring of TPA infusion with external ultrasound is safe and will not result in higher rates of symptomatic intracerebral hemorrhage compared to controls. 3. Data generated during this Phase II trial will form the basis for a design of a properly powered multicenter Phase III trial.